Modern military operations depend on the timely acquisition of intelligence information by electro-optic, infrared, and radio frequency (RF) sensors. Specialized RF sensors have long been used to geolocate radio frequency transmitters used by opposing forces. However, these systems require a substantial investment in expensive equipment and highly trained personnel. Consequently, concepts for exploiting technical advances to network relatively low cost autonomous RF sensors for geolocating radio frequency transmitters are of practical interest.
Approaches based on the use of power measurements are of particular interest due to the simplicity of the sensors, especially the antenna. The basic concept of the power difference of arrival (PDOA) geolocation technique is that, using a suitable path loss model, a geolocation estimate can be obtained from power-level measurements for any type of electro-magnetic wave or an energy emitter from one mobile sensor or an array of sensors.
Finding a suitable path loss model has complicated use of the PDOA geolocation technique. Any number of environmental factors, including concrete structures, windows, and trees, vary the propagation exponent and thereby inject measurement errors into the location calculation, making an accurate location of the transmitter difficult to discern. Finding suitable path loss model that allows for the assumption of a substantially constant path loss exponent for the RF signal as it travels through a medium would make the PDOA geolocation technique very useful.